Temperature-dependent interphase formation and Li+ transport in lithium metal batteries

Abstract

High-performance Li-ion/metal batteries working at a low temperature (i.e., <−20 °C) are desired but hindered by the sluggish kinetics associated with Li+ transport and charge transfer. Herein, the temperature-dependent Li+ behavior during Li plating is profiled by various characterization techniques, suggesting that Li+ diffusion through the solid electrolyte interface (SEI) layer is the key rate-determining step. Lowering the temperature not only slows down Li+ transport, but also alters the thermodynamic reaction of electrolyte decomposition, resulting in different reaction pathways and forming an SEI layer consisting of intermediate products rich in organic species. Such an SEI layer is metastable and unsuitable for efficient Li+ transport. By tuning the solvation structure of the electrolyte with a lower lowest unoccupied molecular orbital (LUMO) energy level and polar groups, such as fluorinated electrolytes like 1 mol L−1 lithium bis(fluorosulfonyl)imide (LiFSI) in methyl trifluoroacetate (MTFA): fluoroethylene carbonate (FEC) (8:2, weight ratio), an inorganic-rich SEI layer more readily forms, which exhibits enhanced tolerance to a change of working temperature (thermodynamics) and improved Li+ transport (kinetics). Our findings uncover the kinetic bottleneck for Li+ transport at low temperature and provide directions to enhance the reaction kinetics/thermodynamics and low-temperature performance by constructing inorganic-rich interphases.

Balancing polysulfide containment and energy loss in lithium–sulfur batteries

“…4d), resulting in similarly low E a-Li + values of 0.095 eV and 0.064 eV, respectively. However, the low E a-Li + for the GO-modified separator is an artifact of the Arrhenius model 20,54–56 due to the near-zero Li + flux through the GO membrane in this temperature range ( i.e. , from 10 to 60 °C).…”

“…However, the low E a-Li + for the GO-modified separator is an artifact of the Arrhenius model 20,[54][55][56] due to the near-zero Li + flux through the GO membrane in this temperature range (i.e., from 10 to 60 1C).…”

Recent advances in designing solid-state electrolytes to reduce the working temperature of lithium batteries

“…The main bottleneck of liquid batteries at low temperatures is focused on the interface, such as the difficulty of desolvation and the deterioration of the SEI conductivity. 166,167 SSBs not only face similar problems, but also suffer from more limitations from Li + conduction in the bulk phase. 55 We think that the difficulty of Li + transfer in the bulk phase is the main bottleneck.…”

Recent progress in SEI engineering for boosting Li metal anodes

“…71 Similarly, recent studies have found that the reactive kinetic barrier for the lithium deposition process was increased at low temperatures, and the Li + transport process through the SEI was slowed down, leading to an increase in polarization. 72 In contrast to room temperature, the battery CE was worse at higher temperatures. However, in the ether-based electrolyte system, the results were different from the conventional carbonate system.…”